共查询到20条相似文献,搜索用时 15 毫秒
1.
Super-microporouos silicon material with high hydrothermal stability denoted as MCM-41-T has been prepared from mesoporous
MCM-41 by high temperature treatment. The structural and chemical property of MCM-41-T has been characterized by X-ray diffraction,
transmission electron microscopy, N2 adsorption-desorption, infrared spectroscopy and 29Si MAS NMR. The characteristic results show that Si-OH groups are forced to condense by high temperature treatment, and the
pore size of MCM-41-T is around 1.5 nm in the super-microporous range. Compared with the original material MCM-41, the hydrothermal
stability of MCM-41-T has been significantly enhanced. 相似文献
2.
Zr-based MCM-41 mesoporous molecular sieves (ZrMCM-41) were successfully synthesized by microwave irradiation method and hydrothermal
method, respectively. The obtained samples were characterized by XRD, TEM, FT-IR and N2 physical adsorption. The results show that the samples synthesized by the two different methods both possess typical hexagonal
mesoporous structure of MCM-41 and high specific surface areas (over 800 m2/g). After calcination at 750°C for 3 h or hydrothermal treatment at 100°C for 6 days, the mesoporous structure of the samples
still retained, however, the mesoporous ordering is poor. Under the comparable conditions, the reaction time required in the
synthesis of ZrMCM-41 by microwave irradiation method was greatly reduced, and microwave irradiation method is eco-friendly
and is easy to operate. 相似文献
3.
Organic modified mesoporous MCM-41 through solvothermal process as drug delivery system 总被引:1,自引:0,他引:1
MCM-41 materials modified by organic aminopropyl groups have been successfully prepared through solvothermal process and have been used as drug-controlled delivery system of aspirin. The results show that the releasing properties of this delivery system are affected by the amount of aminopropyl groups on the pore wall and the ordered structure of mesoporous materials. These materials were characterized by XRD, TG, FT-IR, TEM, UV and N2 adsorption. 相似文献
4.
Hierarchical MCM-41/MFI composites were synthesized through ion-exchange of as-made MCM-41 type mesoporous materials with tetrapropylammonium bromide and subsequent steam-assisted recrystallization. The obtained samples were characterized by powder X-ray diffraction (XRD), UV–vis diffuse reflectance spectroscopy, scanning electron microscopy (SEM), transmission electron microscopy (TEM), thermogravimetric analysis, FT-IR, 1H–13C CP/MAS and nitrogen adsorption–desorption. The XRD patterns show that the MCM-41/MFI composite possesses both ordered MCM-41 phase and zeolite MFI phase. SEM and TEM images indicate that the recrystallized materials retained the mesoporous characteristics and the morphology of as-made mesoporous materials without the formation of bulky zeolite, quite different from the mechanical mixture of MCM-41 and MFI structured zeolite. Among others, lower recrystallization temperature and the introduction of the titanium to the parent materials are beneficial to preserve the mesoporous structure during the recrystallization process. 相似文献
5.
Baoshan Li Junqing Xu Xiao Li Jianjun Liu Shengli Zuo Zhiyun Pan Ziyu Wu 《Materials Research Bulletin》2012,47(5):1142-1148
The MFI/MCM-41 composite material with bimetallic Fe and Co incorporation was prepared using templating method via a two-step hydrothermal crystallization procedure. The obtained products were characterized by a series of techniques including powder X-ray diffraction, N2 sorption, transmission electron microscopy, scanning electron microscope, H2 temperature programmed reduction, thermal analyses, and X-ray absorption fine structure spectroscopy of the Fe and Co K-edge. The catalytic properties of the products were investigated by residual oil hydrocracking reactions. Characterization results showed that the FeCo-MFI/MCM-41 composite simultaneously possessed two kinds of stable meso- and micro-porous structures. Iron and cobalt ions were incorporated into the silicon framework, which was confirmed by H2 temperature programmed reduction and X-ray absorption fine structure spectroscopy. This composite presented excellent activities in hydrocracking of residual oil, which was superior to the pure materials of silicate-1/MCM-41. 相似文献
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8.
Highly ordered mesoporous materials were successfully synthesized by using the iron ore tailings as the silica source and n-hexadecyltrimethyl ammonium bromide as the template. The samples were detail characterized by powder X-ray diffraction, scanning electron microscope, high-resolution transmission electron microscopy and N2 physisorption. The as-synthesized materials had high surface area of 527 m2 g−1 and the mean pore diameter of 2.65 nm with a well-ordered two-dimensional hexagonal structure. It is feasible to prepare mesoporous MCM-41 materials using the iron ore tailings as precursor. 相似文献
9.
通过水热合成法制备MCM-41型介孔分子筛,采用浸渍法负载磷钨酸于MCM-41介孔分子筛中,煅烧得到新型HPW/MCM-41固载催化剂。利用傅里叶红外光谱(FT-IR)、X射线衍射(XRD)、热重分析(TG)和扫描电镜(SEM)对固载催化剂进行表征;考察催化剂对棉纤维催化降解反应的性能。结果表明,新型HPW/MCM-41固载催化剂即持有了磷钨酸的Keggin结构,同时又保持了分子筛的完整介孔结构,具有催化、筛分双重性能。棉纤维催化降解反应数据显示,磷钨酸负载量、反应温度、催化剂用量、液固比及停留时间均影响HPW/MCM-41降解纤维素的性能。在单因素实验最佳反应条件下,棉纤维素降解产物的分子量分布较为均匀,降解产物的产率较优。 相似文献
10.
Irina Ursachi Aurelia Vasile Adelina Ianculescu Eugeniu Vasile Alexandru Stancu 《Materials Chemistry and Physics》2011
Iron oxide nanoparticles were stabilized within the pores of mesoporous silica MCM-41 amino-functionalized by a sonochemical method. Formation of iron oxide nanoparticles inside the mesoporous channels of amino-functionalized MCM-41 was realized by wet impregnation using iron nitrate, followed by calcinations at 550 °C in air. The effect of functionalization level on structural and magnetic properties of obtained nanocomposites was studied. The resulting materials were characterized by powder X-ray diffraction (XRD), high-resolution transmission electron microscopy and selected area electron diffraction (HRTEM and SAED), vibrating sample and superconducting quantum interface magnetometers (VSM and SQUID) and nitrogen adsorption–desorption isotherms measurements. The HRTEM images reveal that the most of the iron oxide nanoparticles were dispersed inside the mesopores of silica matrix and the pore diameter of the amino-functionalized MCM-41 matrix dictates the particle size of iron oxide nanoparticles. The obtained material possesses mesoporous structure and interesting magnetic properties. Saturation magnetization value of magnetic iron oxide nanopatricles stabilized in MCM-41 amino-functionalized by in situ sonochemical synthesis was 1.84 emu g−1. An important finding is that obtained magnetic nanocomposite materials exhibit enhanced magnetic properties than those of iron oxide/MCM-41 nanocomposite obtained by conventional method. The described method is providing a rather short preparation time and a narrow size distribution of iron oxide nanoparticles. 相似文献
11.
Lianzhou Wang S. Velu S. Tomura F. Ohashi K. Suzuki M. Okazaki T. Osaki M. Maeda 《Journal of Materials Science》2002,37(4):801-806
A new series of mesoporous silica spheres containing nanodispersed copper oxides were synthesized in H2O/EtOH/ammonia solution at room temperature. The mesoporous structures were characterised using X-ray powder diffraction and N2 adsorption-desorption techniques. Scanning electron micrograph and transmission electron micrograph revealed that the MCM-41 particles have spherical morphologies. The DTA curve of pure MCM-41 exhibited a sharp single exothermic peak between 290°C and 340°C, while a broad peak with several shoulders in the temperature range between 180°C and 380°C was observed for Cu-MCM-41, indicating the possible complexation of Cu2+ with surfactants adhering to the inner surfaces of the mesopores. Electron paramagnetic resonance spectra of uncalcined samples revealed that Cu2+ ions are in an octahedral or distorted octahedral coordination with nitrogen ligands of the surfactant while in the calcined samples they are coordinated with oxygen of the MCM-41 framework. The redox properties of samples were examined by a temperature-programmed reduction and N2O passivation method. The results indicate that CuO with increasing particle size could be formed in the mesoporous materials with increasing Cu contents, and this decreased the reducibility of the resulting CuO. 相似文献
12.
E. Kraleva M. L. Saladino A. Spinella G. Nasillo E. Caponetti 《Journal of Materials Science》2011,46(22):7114-7120
MCM-41 and Al–MCM-41 has been synthesized using cetyl-trimethylammonium bromide (CTAB) surfactant as template and adding the
silica precursor to aqueous solutions containing CTAB. The obtained solids were calcined at 600 °C for 4 h. HPW heteropolyacid
supported on the mesoporous were prepared using the incipient wetness method. The characterization of materials was performed
by X-ray diffraction, Transmission Electron Microscopy, N2 adsorption, 29Si Cross Polarization–Magic Angle Spinning and 27Al MAS NMR. Results showed that the hexagonal structure is obtained in both cases. The Aluminium species are located inside
an extra-framework. The impregnation reduces the surface area of the mesoporous materials especially of the Al–MCM-41 suggesting
a participation of aluminium during the impregnation. HPW is well dispersed in the mesoporous materials and is located inside
the pores interacting with the silanol group of the pores wall. 27Al MAS NMR measurements have showed that the impregnation causes the removal of the non-framework aluminium. 相似文献
13.
《Materials science & engineering. C, Materials for biological applications》2003,23(6-8):1001-1005
Micro/mesoporous composite material is prepared via reaction of zeolite Beta seeds solution and mesoporous precursor solution under hydrothermal conditions. The resulted micro/mesoporous composite contains nanoparticles with a mean radius of about 90 nm, while pure zeolite Beta and MCM-41 have particles with size of about 50 and 230 nm, respectively. The presence of highly cross-linked silicon framework walls and tetrahedrally coordinated aluminum in the framework structure are confirmed with solid-state 29Si and 27Al NMR investigations. Adsorption measurements show the presence of micropores, mesopores and high interparticle porosity due to the nanometer-sized particles in the micro/mesoporous composite. Various techniques such as dynamic light scattering, scanning electron microscopy, X-ray diffraction, FT-IR, NMR spectroscopy and nitrogen sorption measurements were carried out in order to investigate the properties of the prepared material. 相似文献
14.
A new and efficient method for the preparation of MCM-41 type ordered mesoporous phases using phosphate as promoter under
reflux conditions is reported. The various mesoporous materials studied were: silica (Si-MCM-41), alumino-silicate (Al-MCM-41),
and titanium-silicate (Ti-MCM-41). Our concept of promoter-assisted synthesis of zeolites and related microporous materials
was found to be applicable in the synthesis of ordered mesoporous materials as well. The addition of small catalytic quantity
of phosphate ions (PO
4
3−
), used as promoters, significantly reduced the synthesis time (by a factor of 3–4) of all these mesoporous materials. The
synthesis of new MCM-41 type organic-inorganic composite materials with unique properties is also reported. 相似文献
15.
Electrochemical sensor for detecting ultratrace nitroaromatic compounds using mesoporous SiO2-modified electrode 总被引:1,自引:0,他引:1
An electrochemical sensor for ultratrace nitroaromatic compounds (NACs) using mesoporous SiO2 of MCM-41 as sensitive materials is reported. MCM-41 was synthesized and characterized by scanning electron microscope, transmission electron microscopy, and small-angle X-ray diffraction. Glassy carbon electrodes modified with MCM-41 show high sensitivity for cathodic voltammetric detection of NACs (including 2,4,6-trinitrotoluene (TNT), 1,3,5-trinitrobenzene (TNB), 2,4-dinitrotoluene, and 1,3-dinitrobenzene) down to the nanomolar level. The high sensitivity is attributed to the strong adsorption of NACs by MCM-41 and large surface area of the working electrode resulting from MCM-41 modification. The voltammetric response is fast, and the detection of NACs can be finished within 14 s. SiO2 nanospheres were similarly used to modify glassy carbon electrodes for electrochemical detection of TNT and TNB. The detection limit of SiO2 nanosphere-modified electrodes is lower than that of MCM-41-modified electrodes, possibly due to the smaller surface area of SiO2 nanospheres than mesoporous MCM-41. The results show mesoporous SiO2-modified glassy carbon electrodes, particularly MCM-41-modified electrodes, open new opportunities for fast, simple, and sensitive field analysis of NACs. 相似文献
16.
Sergio L. González-Cortés Tian-Cun Xiao Nick Rees Dora Méhn Malcolm L.H. Green 《Materials Research Bulletin》2005,40(7):1112-1119
The first examples of mesostructured materials containing Mo- and W-oxo-sulphur species incorporated into a poorly ordered MCM-41 framework have been prepared under hydrothermal condition and alkaline medium. The incorporation of oxygen-sulphur derivates of molybdenum and tungsten not only increases significantly the pore diameter, but also improves the thermal stability of the MCM-41-related mesoporous material. 相似文献
17.
Cobalt-containing MCM-41 and SBA-15 mesoporous materials were prepared by the pH-adjusting of the impregnation solution. The
modified materials were investigated by X-ray diffraction, N2 physisorption, temperature-programmed reduction, DR UV–Vis diffuse reflectance, and FT-IR spectroscopy of adsorbed pyridine.
The pH of the impregnation solution influences the surface charge of the mesoporous support and therefore determines the strength
of interaction between the cobalt precursor and the mesoporous support. The formation of different cobalt oxide species in
different ratios, depending on the pH of the impregnation solution, was established for both materials. The modified Co/MCM-41
and Co/SBA-15 materials were active in toluene oxidation. Their catalytic activity is predetermined by the nature, the reducibility,
and the dispersion of the obtained cobalt oxide species. 相似文献
18.
Methyl group functionalized Zr-MCM-41 was synthesized by the hydrothermal method. The obtained Me-Zr-MCM-41 materials were characterized by X-ray diffraction, N2 physisorption, transmission electron microscopy, Fourier transform infrared spectroscopy and Ultraviolet-visible diffuse reflectance spectroscopy. The results indicated that Zr was highly dispersed in the framework of MCM-41, and methyl group was stable enough to endure the acid treatment for removing the template. The measurement results of the surface hydrophobic/hydrophilic properties showed that the surface hydrophobicity of Me-Zr-MCM-41 materials increased with increasing the content of methyl groups. 相似文献
19.
Polypropylene(PP)/Polystyrene(PS) (PP/PS = 80/20) blend with different types of fillers were prepared by using melt method. Four different types of fillers, namely mesoporous MCM-41 (without template), nano-SiO2, Polymethylmethacrylate (PMMA)/MCM-41 and PMMA/SiO2 were considered. For PMMA/MCM-41 filler, the synthesis of the filler consisting of entrapped strand of PMMA within the pores of mesoporous MCM-41 (without template) was described. The mechanical properties of the blend determined as the nano-fillers contents and the different types of blend were found to vary with the different interface between fillers and the matrix. SEM revealed a good interaction between the matrix phases and PMMA/MCM-41 or MCM-41 (without template). The decreased Tg of PS implied that the good adhesion between PP and PS blend was obtained by adding PMMA/MCM-41 nano-filler. 相似文献
20.
《Advanced Powder Technology》2022,33(2):103417
In this study, mesoporous silica nanoparticles (MSNs) composed of MCM-41 were synthesized and modified with amine groups (i.e., NH2) to form NH2/MCM-41, which was loaded with curcumin (CUR) to form CUR@NH2/MCM-41 to create an efficient carriers in drug delivery systems (DDSs). The three samples (i.e., pure MCM-41, NH2/MCM-41, and CUR@NH2/MCM-41) were characterized using X-ray diffraction (XRD), Brunauer-Emmett-Teller (BET) surface area, Fourier-transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX), transition electron microscopy (TEM), and a thermogravimetric analyzer (TGA). The study investigated the effect of the carrier dose, CUR concentration, pH, and contact time on the drug loading efficiency (DLE%) by adsorption. The best DLE% for MCM-41 and NH2/MCM-41 was found to be 15.78 and 80%, respectively. This data demonstrated that the Langmuir isotherm had a greater correlation coefficient (R2) of 0.9840 for MCM-41 and 0.9666 for NH2/MCM-41 than the Freundlich and Temkin isotherm models. A pseudo-second-order kinetic model seems to fit well with R2 = 0.9741 for MCM-41 and R2 = 0.9977 for NH2/MCM-41. A phosphate buffer solution (PBS) with a pH of 7.4 was utilized to study CUR release behavior. As a result, the full release after 72 h was found to have a maximum of 74.1% and 29.95% for pure MCM-41 and NH2/MCM-41, respectively. The first-order, Weibull, Hixson-Crowell, Korsmeyer-Peppas, and Higuchi kinetic release models were applied to releasing CUR from CUR@MCM-41 and CUR@NH2/MCM-41. The Weibull kinetic model fit well, with R2 = 0.944 and 0.96912 for pure MCM-41 and NH2/MCM-41, respectively. 相似文献